I got an 88 dx crx with a b16a2 I was told from the person I bought the motor from that is was rebuilt and when I first started it, it made a small knocking noise in the head when I would let go of the throttle. I was told it was the lmas and I changed them to skunk2 lmas. We started it again and it sounded fine but after 20 minutes of letting it run it made a louder knocking noise in the head by the timing belt. Anyone got ideas on what the problem is?

 

Did you also adjust your valve lash? Did everything in the head look okay? Any rocker pad or camshaft wear?

It may be a longshot but it may be worth it to check your timing belt tension as well. They can make a slapping noise if not tensioned properly.